Lincoln University Information Technology

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Exchange Users Cannot Send Mail to Addresses -- Resolved

3/20/03 Initial Problem (view history ): Staff with addresses who have been migrated to Exchange suddenly cannot mail to addresses for those who are not yet configured to use Exchange. Mail to other domains and other Lincoln hosts is functioning normally. Incoming mail is functioning normally. This is a priority 1 problem, as it affects several IT users and interrupts communication. Consultants have been engaged, and numerous tests have been conducted to isolate symptoms.

The configuration of Outlook for Exchange users while we continue to use SMTP/POP3 on the Alpha was found to be unstable and one that Microsoft does not support. Several layers of mail forwarding have been implemented for users who are not yet on Exchange in order to deliver mail reliably.

Some technical detail:

Microsoft does not support using both Exchange and Internet mail services in a single Outlook profile, and has seen the symptoms we're experiencing, where the client-server Exchange+SMTP system works for a while and then fails. This configuration was used because two machines must believe they are - Exchange, for mail between Exchange users, and the Alpha for all other mail to Solution - force Exchange to deliver all mail.

All addresses must therefore be known to the Exchange server, but at the same time accounts for those with lu addresses who do not yet use Exchange must remain valid and operationally unchanged on the Alpha. Those users' delivery addresses are "foreign" to Exchange, so we must simulate a foreign address for them. To implement this we must create contact objects in the Active Directory for users who are not live on Exchange, containing addresses at We add Exchange mailboxes to the users' domain accounts and forward all mail to their individual contact, which has a foreign address. Mail from Exchange users to, for example, will be forwarded to in turn has a Sendmail alias for each of those users that forwards mail to (the Alpha) along the path taken by mail from off campus.

This complicated arrangement need only last until all Alpha users are using Exchange, either through Outlook or through Outlook Web Access.

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